Turbines are widely used in industrial and commercial operations. A typical commercial steam or gas turbine used to generate electrical power includes alternating stages of stationary and rotating airfoils. For example, stationary vanes may be attached to a stationary component such as a casing that surrounds the turbine, and rotating blades may be attached to a rotor located along an axial centerline of the turbine. A compressed working fluid, such as but not limited to steam, combustion gases, or air, flows through the turbine, and the stationary vanes accelerate and direct the compressed working fluid onto the subsequent stage of rotating blades to impart motion to the rotating blades, thus turning the rotor and performing work.
An efficiency of the turbine generally increases with increased temperatures of the compressed working fluid. However, excessive temperatures within the turbine can reduce the longevity of the airfoils in the turbine and thus increase repairs, maintenance, and outages associated with the turbine. As a result, various designs and methods have been developed to provide cooling to the airfoils. For example, a cooling media can be supplied to a cavity inside the airfoil to convectively and/or conductively remove heat from the airfoil. In particular embodiments, the cooling media can flow out of the cavity through cooling passages in the airfoil to provide film cooling over the outer surface of the airfoil.
As temperatures and/or performance standards continue to increase, the materials used for the airfoil become increasingly thin, making reliable manufacture of the airfoil increasingly difficult. For example, certain airfoils are cast from a high alloy metal, with a thermal barrier coating applied to the outer surface of such airfoils to enhance thermal protection. Through continued use, however, the cooling holes in the airfoils can become clogged with debris or other contaminates and the thermal barrier coating can become worn down or chipped. Additionally, in certain cases, the airfoil can undergo plastic deformation such that the location and/or orientation of the holes may change from an original location and/or orientation.
Certain airfoils can be repaired to address the above issues. However, it is generally an expensive and time consuming process to correctly clear out each of the cooling holes and re-apply a thermal barrier coating. Accordingly, a system and method for determining the locations and/or orientations of each of the cooling holes would be useful. Further, a system and method for both determining which, if any, of the cooling holes are clogged and for removing any debris would be particularly beneficial.